1. Earth moves somewhat faster than Mars, but much faster than Saturn as it orbits the Sun. Earth can "lap" Saturn in only a bit over one Earth year, so in 378 days Saturn will be seen at oppostion again. (Earth's orbital speed is 30 km/sec and Saturn's is 9.6 km/sec.) Mars' mean orbital speed is 24 km/sec and therefore Earth takes 780 days to "lap" Mars and bring it back to opposition.